Combustion engines that operate using a reciprocating piston suffer from a number of disadvantages. First and foremost is the inefficient manner in which components such as, for example, pistons are repeatedly accelerated, stopped, and reversed during operation of the engine. In this regard, conventional piston-based engines are both unbalanced and inefficient due to the constant momentum changes occurring within the engine. It has been estimated, for example, that about 13% of fuel energy is lost in a conventional piston-based engine due to internal friction and pumping losses.
In addition, in conventional piston-based engines, there is only a brief moment (if at all) when the torque arm is in its optimum configuration with the piston/connecting rod. This typically occurs a few degrees before the middle of the piston stroke. In fact, a true 90° (optimal) torque arm is never achieved in a conventional piston-based combustion engine.
The internal combustion rotary engine is one alternative to piston-based combustion engines which can mitigate, to some extent, these inherent inefficiencies. Felix Wankel is credited with inventing an internal combustion rotary engine which operates by using a triangular-shaped rotor spinning within a housing shaped in the manner of a epitrochoid (e.g., peanut-shaped). The internal combustion rotary engine includes a number of advantages over piston-based combustion engines.
First, internal combustion rotary engines are more lightweight and compact. Second, internal combustion rotary engines are smoother since there is no reciprocating motion of pistons. Third, internal combustion rotary engines have an extended power stroke rotation of the output shaft as compared to their piston-based counterparts. Fourth, there are fewer moving parts, e.g., no valves, connecting rods, cams, and timing chains. Timing of the intake and exhaust strokes are accomplished directly by the motion of the rotor. Fifth, internal combustion rotary engines have a generally flat torque curve because no valves are used. Sixth, combustion in internal combustion rotary engines are generally cooler than their piston-based counterparts. This means fewer oxides of nitrogen are created. Finally, internal combustion rotary engines separate the combustion region from the intake region, thereby making these engines good candidates for hydrogen fuel-based engines.
The problem with Wankel-type internal combustion rotary engines is that they generally leak combustion gases, making these types of engines less desirable. In addition, the rotational speed (i.e., revolutions per minute (RPM)) of Wankel-type internal combustion rotary engines is limited because of the manner in which the triangular rotor flip-flops around the interior of the epitrochoid housing.
There thus is a need for a true internal combustion rotary engine that is not limited in its rotational speed. In addition, there is a need for an internal combustion rotary engine that has very low emissions. In addition, there is a need for an internal combustion rotary engine that has high horsepower and high torque while at the same time is fuel efficient.